I'm already enthrald in the unique alien designs and gorgeous imperial coloring! Seriously, you have something here! The hip (Plates?) are something I've never seen before and everything just flows so perfectly from one body part to another! It's, as the English & the Doctor would say, brilliant!
Fire? Well . . . I have no idea how to explain it. I've only drawn it succesfully once. I'd say, if your trying for small balls of fire, you just mae a roud base and the add a central, slightly wavy, tongue of flame, then add two or three more. Seperating the very top of a flame-tongue to is also good to do. Good luck with it!

Well, thanks but the design is not mine. Ember is a character from a game developed by Digital Extremes, Warframe.
This more a exercise/fan art to see my limitations since I don't have that much experience with colors, mostly of my drawings consisted of graphite with shading.